Trimethylchlorosilane was used as a stereoselective reagent to determine the e or a orientation of 3-hydroxyl group of some steroids by chemical ionization mass spectrometry.
Selective laser melting(SLM)is a unique additive manufacturing(AM)category that can be used to manufacture mechanical parts.It has been widely used in aerospace and automotive using metal or alloy powder.The build ori...Selective laser melting(SLM)is a unique additive manufacturing(AM)category that can be used to manufacture mechanical parts.It has been widely used in aerospace and automotive using metal or alloy powder.The build orientation is crucial in AM because it affects the as-built part,including its part accuracy,surface roughness,support structure,and build time and cost.A mechanical part is usually composed of multiple surface features.The surface features carry the production and design knowledge,which can be utilized in SLM fabrication.This study proposes a method to determine the build orientation of multi-feature mechanical parts(MFMPs)in SLM.First,the surface features of an MFMP are recognized and grouped for formulating the particular optimization objectives.Second,the estimation models of involved optimization objectives are established,and a set of alternative build orientations(ABOs)is further obtained by many-objective optimization.Lastly,a multi-objective decision making method integrated by the technique for order of preference by similarity to the ideal solution and cosine similarity measure is presented to select an optimal build orientation from those ABOs.The weights of the feature groups and considered objectives are achieved by a fuzzy analytical hierarchy process.Two case studies are reported to validate the proposed method with numerical results,and the effectiveness comparison is presented.Physical manufacturing is conducted to prove the performance of the proposed method.The measured average sampling surface roughness of the most crucial feature of the bracket in the original orientation and the orientations obtained by the weighted sum model and the proposed method are 15.82,10.84,and 10.62μm,respectively.The numerical and physical validation results demonstrate that the proposed method is desirable to determine the build orientations of MFMPs with competitive results in SLM.展开更多
In order to understand the possible mechanisms responsible for the superconductivity of high T_c oxides, the study of their structures and physical properties is in progress worldwide. The samples investigated are bei...In order to understand the possible mechanisms responsible for the superconductivity of high T_c oxides, the study of their structures and physical properties is in progress worldwide. The samples investigated are being changed from polycrystallines to single crys-展开更多
This paper proposes an artificial neural network to determine orientation using polarized skylight. This neural network has specific dilated convolution, which can extract light intensity information of different pola...This paper proposes an artificial neural network to determine orientation using polarized skylight. This neural network has specific dilated convolution, which can extract light intensity information of different polarization directions. Then, the degree of polarization (DOP) and angle of polarization (AOP) are directly extracted in the network. In addition, the exponential function encoding of orientation is designed as the network output, which can better reflect the insect’s encoding of polarization information and improve the accuracy of orientation determination. Finally, training and testing were conducted on a public polarized skylight navigation dataset, and the experimental results proved the stability and effectiveness of the network.展开更多
Our work shows that differdnt compound orientations have different results in Comparative Molecular Field Analysis(CoMFA).For three analyzed compound series,the squared correlation coefficients of cross-validation(q2)...Our work shows that differdnt compound orientations have different results in Comparative Molecular Field Analysis(CoMFA).For three analyzed compound series,the squared correlation coefficients of cross-validation(q2)could vary as largely as 0.30～0.40 among all possible orientations.THe reason for this comes from the routine adopted by CoMFA which uses discrete,regularly arrayed grids to represent the molecular field.Therefore,different orientatins may map their molecular fields differently onto the grid and accordingly give different results from partial least square(PLS)analyses.We have developed a method all-orientation searching,to seek for the orientation with the best CoMFA result. And ,we suggest that all-orietnation searching shoule be incorporated intto the standard CoMFA procedurd.展开更多
文摘Trimethylchlorosilane was used as a stereoselective reagent to determine the e or a orientation of 3-hydroxyl group of some steroids by chemical ionization mass spectrometry.
基金ACKNOWLEDGEMENTS We especially thank the National Science Foundation of China （70771009, 71071017） and the Fundamental Research Funds for the Central Universities （FRF-BR-09-019） for supporting this research.
基金funded by the National Key R&D Program of China(Grant No.2018YFB1700700)the National Natural Science Foundation of China(Grant Nos.51935009 and 51821093).
文摘Selective laser melting(SLM)is a unique additive manufacturing(AM)category that can be used to manufacture mechanical parts.It has been widely used in aerospace and automotive using metal or alloy powder.The build orientation is crucial in AM because it affects the as-built part,including its part accuracy,surface roughness,support structure,and build time and cost.A mechanical part is usually composed of multiple surface features.The surface features carry the production and design knowledge,which can be utilized in SLM fabrication.This study proposes a method to determine the build orientation of multi-feature mechanical parts(MFMPs)in SLM.First,the surface features of an MFMP are recognized and grouped for formulating the particular optimization objectives.Second,the estimation models of involved optimization objectives are established,and a set of alternative build orientations(ABOs)is further obtained by many-objective optimization.Lastly,a multi-objective decision making method integrated by the technique for order of preference by similarity to the ideal solution and cosine similarity measure is presented to select an optimal build orientation from those ABOs.The weights of the feature groups and considered objectives are achieved by a fuzzy analytical hierarchy process.Two case studies are reported to validate the proposed method with numerical results,and the effectiveness comparison is presented.Physical manufacturing is conducted to prove the performance of the proposed method.The measured average sampling surface roughness of the most crucial feature of the bracket in the original orientation and the orientations obtained by the weighted sum model and the proposed method are 15.82,10.84,and 10.62μm,respectively.The numerical and physical validation results demonstrate that the proposed method is desirable to determine the build orientations of MFMPs with competitive results in SLM.
文摘In order to understand the possible mechanisms responsible for the superconductivity of high T_c oxides, the study of their structures and physical properties is in progress worldwide. The samples investigated are being changed from polycrystallines to single crys-
基金Funding was provided by the National Key Research and Development Program of China(Grant No.2021ZD0200300)National Natural Science Foundation of China(NSFC)(U2031138).
文摘This paper proposes an artificial neural network to determine orientation using polarized skylight. This neural network has specific dilated convolution, which can extract light intensity information of different polarization directions. Then, the degree of polarization (DOP) and angle of polarization (AOP) are directly extracted in the network. In addition, the exponential function encoding of orientation is designed as the network output, which can better reflect the insect’s encoding of polarization information and improve the accuracy of orientation determination. Finally, training and testing were conducted on a public polarized skylight navigation dataset, and the experimental results proved the stability and effectiveness of the network.
文摘Our work shows that differdnt compound orientations have different results in Comparative Molecular Field Analysis(CoMFA).For three analyzed compound series,the squared correlation coefficients of cross-validation(q2)could vary as largely as 0.30～0.40 among all possible orientations.THe reason for this comes from the routine adopted by CoMFA which uses discrete,regularly arrayed grids to represent the molecular field.Therefore,different orientatins may map their molecular fields differently onto the grid and accordingly give different results from partial least square(PLS)analyses.We have developed a method all-orientation searching,to seek for the orientation with the best CoMFA result. And ,we suggest that all-orietnation searching shoule be incorporated intto the standard CoMFA procedurd.
